The present invention pertains in general to transmission line oscillators and more particularly to transmission line oscillators having two degrees of freedom.
The need for an oscillator with a specific Q.sub.ext arises from the requirements of specific applications. For example, when an oscillator is to be used in an injection locking mode, the Q.sub.ext must be low. The actual value of Q.sub.ext depends upon the locking bandwidth and the desired gain. On the other hand, when having a low residual noise of the oscillator is paramount, the Q.sub.ext must be high.
In existing circuits where both the input impedance seen by the active device and the Q.sub.ext are a function of the coupling coefficient, it is not possible to construct such an oscillator to have a specific Q.sub.ext because such an oscillator has only one degree of freedom, which is used to establish the oscillation condition.
Therefore, it is desirable to have a circuit which satisfies both the conditions of sustained oscillation and the requirement for a specific Q.sub.ext independently.